1. Field of the Invention
The present invention relates to power management in electronic systems, including techniques for power managing rack-mounted servers.
2. Description of the Related Art
Servers and other computer hardware are often grouped together on a rack to conserve space and place the servers and infrastructure in a central location for access by an administrator. Managing these “rack systems” can be less difficult and less expensive than separately administering a multitude of scattered servers. A variety of rack system designs are available in the market, and range in size and density. Some rack systems use essentially standalone servers deployed in rack-mounted or tower configuration. A higher density rack system can be realized using blade servers, which may be implemented as thin, pluggable boards that slide into a chassis designed specifically to house multiple units. Blade servers generally have a narrower form factor and greater density, achieved in part due to sharing system resources such as cooling and power. Some of the more compact rack system server arrangements presently available include the SYSTEM X servers and eServer BLADECENTER available from IBM (IBM, BLADECENTER, and SYSTEM X are registered trademarks of International Business Machines Corporation, Armonk, N.Y.).
Power management is important for controlling many aspects of operating a rack system, such as the costs of operating the servers, the heat generated by the servers, and the performance and efficiency of the system. A variety of power management options are available. Some systems limit (“cap”) server energy consumption by measuring power draw and instantaneously responding to increases in power consumption by invoking a throttling mechanism when a power threshold is reached. Other systems are targeted more toward controlling average power excursions over time. The IBM PowerExecutive™ is an example of a power management system available for selected IBM BLADECENTER and SYSTEM X servers, allowing direct power monitoring through the IBM Director management interface. This can be beneficial for customers who must operate a system within a fixed power constraint, or who want to budget a certain amount of power to a group of servers. Further examples of power management schemes are provided in U.S. Pat. No. 7,155,623 to IBM, disclosing a “Method and System for Power Management Including Local Bounding of Device Group Power Consumption,” and U.S. Patent Application Publication No. US 2006/0156042 to IBM, disclosing a “Method, System, and Calibration Technique for Power Measurement and Management Over Multiple Time Frames.” While IBM has pioneered many aspects of power management in server systems, a variety of other power management protocols are also known in the art.
Many power management systems rely on specialized hardware and firmware that increase system cost. For example, one feedback-based power management system may involve a specialized motherboard having a built-in power meter circuit, ACPI, and other hardware and/or software elements for providing the feedback-based power control. While such systems can effectively and reliably manage power, the specialized motherboard configurations are generally more expensive than other industry standard motherboards. An improved power management system is therefore desired in view of the existing art. It would be desirable in some instances to lower system cost by substituting industry standard hardware elements for costlier, proprietary hardware configurations. For example, there is an economic incentive to use “industry standard” system motherboards substantially without modification in computer system products, because modifications (such as on-board power management circuits) increase cost and make the motherboard “non-standard.”